170 lines
3.3 KiB
Scheme
170 lines
3.3 KiB
Scheme
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// Declare uniforms (i.e. device constants)
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uniform Scalar cs2_sound;
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uniform Scalar nu_visc;
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uniform Scalar cp_sound;
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uniform Scalar mu0;
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uniform Scalar eta;
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uniform Scalar gamma;
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uniform Scalar chi;
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uniform Scalar zeta;
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uniform Scalar xorig;
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uniform Scalar yorig;
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uniform Scalar zorig;
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//Star position
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uniform Scalar star_pos_x;
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uniform Scalar star_pos_z;
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uniform Scalar GM_star;
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uniform int nx_min;
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uniform int ny_min;
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uniform int nz_min;
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uniform int nx;
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uniform int ny;
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uniform int nz;
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//Needed for gravity
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uniform Scalar dsx;
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uniform Scalar dsy;
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uniform Scalar dsz;
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uniform Scalar inv_dsx;
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uniform Scalar inv_dsy;
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uniform Scalar inv_dsz;
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Scalar
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distance_x(Vector a, Vector b)
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{
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return sqrt(dot(a-b, a-b));
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}
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Vector
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value(in Vector uu)
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{
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return (Vector){value(uu.x), value(uu.y), value(uu.z)};
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}
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Matrix
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gradients(in Vector uu)
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{
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return (Matrix){gradient(uu.x), gradient(uu.y), gradient(uu.z)};
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}
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Scalar
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continuity(in Vector uu, in Scalar lnrho) {
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return -dot(value(uu), gradient(lnrho)) - divergence(uu);
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}
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// "Line-like" gravity with no y-component
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Vector
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grav_force_line(const int3 vertexIdx)
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{
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Vector vertex_pos = (Vector){dsx * vertexIdx.x - xorig, dsy * vertexIdx.y - yorig, dsz * vertexIdx.z - zorig};
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Vector star_pos = (Vector){star_pos_x, dsy * vertexIdx.y - yorig, dsz * vertexIdx.z - zorig};
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const Scalar RR = vertex_pos.x - star_pos.x;
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const Scalar G_force_abs = GM_star / (RR*RR); // Force per unit mass;
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Vector G_force = (Vector){ - G_force_abs,
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AcReal(0.0),
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AcReal(0.0)};
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return G_force;
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}
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Vector
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momentum(in Vector uu, in Scalar lnrho, const int3 vertexIdx) {
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Vector mom;
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const Matrix S = stress_tensor(uu);
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mom = -mul(gradients(uu), value(uu)) -
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cs2_sound * gradient(lnrho) +
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nu_visc *
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(laplace_vec(uu) + Scalar(1. / 3.) * gradient_of_divergence(uu) +
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Scalar(2.) * mul(S, gradient(lnrho))) + zeta * gradient_of_divergence(uu)
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+ grav_force_line(vertexIdx);
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return mom;
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}
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Vector
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induction(in Vector uu, in Vector aa) {
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// Note: We do (-nabla^2 A + nabla(nabla dot A)) instead of (nabla x (nabla
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// x A)) in order to avoid taking the first derivative twice (did the math,
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// yes this actually works. See pg.28 in arXiv:astro-ph/0109497)
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// u cross B - ETA * mu0 * (mu0^-1 * [- laplace A + grad div A ])
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const Vector B = curl(aa);
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const Vector grad_div = gradient_of_divergence(aa);
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const Vector lap = laplace_vec(aa);
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// Note, mu0 is cancelled out
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const Vector ind = cross(value(uu), B) - eta * (grad_div - lap);
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return ind;
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}
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// Declare input and output arrays using locations specified in the
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// array enum in astaroth.h
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in Scalar lnrho = VTXBUF_LNRHO;
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out Scalar out_lnrho = VTXBUF_LNRHO;
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in Vector uu = (int3) {VTXBUF_UUX, VTXBUF_UUY, VTXBUF_UUZ};
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out Vector out_uu = (int3) {VTXBUF_UUX,VTXBUF_UUY,VTXBUF_UUZ};
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#if LINDUCTION
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in Vector aa = (int3) {VTXBUF_AX,VTXBUF_AY,VTXBUF_AZ};
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out Vector out_aa = (int3) {VTXBUF_AX,VTXBUF_AY,VTXBUF_AZ};
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#endif
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Kernel void
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solve(Scalar dt) {
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WRITE(out_lnrho, RK3(out_lnrho, lnrho, continuity(uu, lnrho), dt));
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#if LINDUCTION
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WRITE(out_aa, RK3(out_aa, aa, induction(uu, aa), dt));
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#endif
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WRITE(out_uu, RK3(out_uu, uu, momentum(uu, lnrho, vertexIdx), dt));
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}
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